Bio 3300 - Cell and Molecular Biology » Summer 2020 » Exam 1
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Question #1
From the following which is the best description for fluorescence microscopy
A.
uses a light microscope with an optical component to take advantage of the different refractive indices of light passing through different regions of the cell
B.
employs a light microscope and requires that samples be fixed and stained in order to reveal cellular details
C.
has the ability to resolve cellular components as small as 2 nm.
D.
requires coating the sample with a thin layer of a heavy metal to produce three dimensional images of the surface of a sample
E.
requires the use of two sets of filters. The first filter narrows the wavelength range that reaches the specimen and the second blocks out all wavelengths that pass back up to the eyepiece except for those emitted by the dye in the sample.
F.
scans the specimen with a focused laser beam to obtain a series of two-dimensional optical sections, which can be used to reconstruct an image of the specimen in three dimensions. The laser excites a fluorescent dye molecule, and the emitted light from each illuminated point is captured through a pinhole and recorded by a detector.
Question #2
The amino acids glutamine and glutamic acid are shown in figure. They differ only in the structure of their side chains (circled). At pH7, glutamic acid can participate in molecular interactions that are not possible for glutamine. What types of interactions are these?
A.
covalent bonds
B.
ionic bonds
C.
van der Waals interactions
D.
hydrogen bonds
Question #3
Water has a specific heat because of the _____
A.
polar covalent bond formed between the oxygen and a hydrogen of single water molecule
B.
covalent bond formed between the hydrogen of one water molecule and the oxygen of another water molecule
C.
ionic bonds formed between the hydrogen of one water molecule and the oxygen of another water molecule
D.
hydrogen bond formed between the hydrogen of one water molecule and the oxygen of another water molecule
Question #4
If a double stranded DNA sample were composed of 10 percent thymine, what would be the percentage of guanine?
A.
40
B.
It is impossible to tell from the information given.
C.
20
D.
10
E.
80
Question #5
Biologists cannot possibly study all living species. Instead, they try to understand cell behavior by studying a select subset of them. Which of the following characteristics are useful in an organism chosen for use as a model in laboratory studies.
A.
amenability to genetic manipulation
B.
ability to grow under controlled conditions.
C.
rapid rate of reproduction
D.
genome partially or completely sequenced
E.
All of the above is correct.
Question #6
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by
A.
van der Waals interactions
B.
hydrogen bonds.
C.
nonpolar covalent bonds
D.
polar covalent bonds
E.
ionic bonds
Question #7
Imagine you are astronaut on Mars expedition and found rock samples containing few cells. How would you determine that the life found on Mars have originated independently and shares no early ancestry with Earth life?
A.
The cells on Mars gain energy by using minerals found only on Mars., not on Earth.
B.
Studies of the earliest Mars and Earth cells show that they can both survive for many years in the harsh vacuum of space
C.
Life on Mars uses a different genetic code (DNA & RNA) than life on Earth
D.
Life on Mars tolerates the much higher levels of radiation found on Mars than life on Earth, which could be poisoned by the radiation
Question #8
In the PBS video, we learned that when modern scientists mimic the early atmosphere of Earth, small organic molecule are able to combine to produce:
A.
complex cells
B.
RNA
C.
ATP
D.
DNA
E.
Ribozyme
Question #9
The ____ is made up of two concentric membranes and is continuous with the membrane of the endoplasmic reticulum
A.
Mitochondrial membrane
B.
nuclear envelope
C.
plasma membrane
D.
Golgi network
Question #10
Some of the drugs used to treat HIV patients are competitive inhibitors of the HIV reverse transcriptase enzyme. Unfortunately, the high mutation rate of HIV means that the virus rapidly acquires mutations with amino acid changes that make them resistant to these competitive inhibitors. Where in the revers transcriptase enzyme would such amino acid changes most likely occur in drug-resistant viruses?
A.
at an allosteric site
B.
in regions of the protein that determine packaging into the virus capsid
C.
in or near the active site
D.
Such mutations could occur anywhere with equal probability
E.
at a cofactor binding site
Question #11
Which of the following is a characteristic of mitochondria and chloroplasts that supports the endosymbiotic theory?
A.
Both contain ribosomes that are identical to ribosomes of the eukaryotic
B.
Both contain endoplasmic reticulum and Golgi bodies.
C.
Both contain DNA molecules
D.
Both have bacteria-like polysaccharide cell walls
E.
Both can reproduce on their own outside of the cell
Question #12
Photosynthesis enables plants to capture the energy from sunlight. In this essential process, plants incorporate the carbon from CO2 into high energy _______ molecules, which the plant cell mitochondria use to produce ATP
A.
protein
B.
fat
C.
fiber
D.
sugar
Question #13
A cell with a predominance of free ribosomes is most likely ______
A.
constructing an extensive cell wall or extracellular matrix
B.
digesting large food particles
C.
primarily producing proteins for secretion
D.
enlarging its vacuole
E.
primarily producing proteins in the cytosol
Question #14
The first task you are assigned in your summer laboratory job is to prepare a concentrated NaOH stock solution. The molecular weight of NaOH is 40. How many grams of solid NaOH will you need to weigh out to obtain a 500 mL solution that has a concentration of 10M?
A.
800g
B.
160g
C.
125g
D.
200g
E.
400g
Question #15
Why do researchers think the first self-replicating molecule was RNA?
A.
Fossil evidence of such a molecule was recently discovered.
B.
RNA can carry information and catalyze chemical reactions
C.
RNA is the only type of molecule that can catalyze a chemical reaction.
D.
Self-replicating molecules of RNA exist today, in human cells
Question #16
Despite the differences between eukaryotic and prokaryotic cells, prokaryotes have proteins that are distantly related to eukaryotic actin filaments and microtubules. What is likely to be the most ancient function of the cytoskeleton?
A.
cell division
B.
cell motility
C.
vesicle transport
D.
membrane support
Question #17
Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei. Which one of these molecules contains polar bonds?
A.
propane
B.
methane
C.
molecular oxygen
D.
water
Question #18
cell biologists employ targeted fluorescent dyes or modified fluorescent proteins in both standard fluorescence miccroscopy and confocal microscopy to observe specific details in the cell. Even though fluorescence permits better visualization, the resolving power is essentially the same as that of a standard light microscope because the resolving power of a microscope is limited by the _____ of light
A.
filtering
B.
wavelength
C.
absorption
D.
intensity
Question #19
The above graph shows the change in free energy as a reaction progresses. Which of the following statements are true of this overall process? This reaction releases energy. This is an endergonic reaction. The ΔG for this reaction is negative. The ΔG for this reaction is positive. An example of this type of reaction is creation of peptide bonds between amino acids to make a protein
A.
1,4,5
B.
1,2,4,5
C.
2,3,5
D.
2,3,5
E.
2,4,5
Question #20
A glycosidic linkage is analogous to which of the following in proteins?
A.
an amino group
B.
a β-Pleated Sheet
C.
a peptide bond
D.
a disulfide bond
Question #21
Instead of studying one or two proteins or protein complexes present in the cell at any given time, we can now look at a snapshot of all proteins being expressed in cells being grown in specific conditions. This large-scale, systematic approach to the study of proteins is called ____?
A.
genomics
B.
systems biology
C.
structural biology
D.
proteomics
Question #22
We have several examples of macromolecules in the cell performing different functions. Most of them are polymers. Which of the following is NOT a polymer?
A.
cellulose
B.
glucose
C.
DNA
D.
starch
E.
Protein
Question #23
If you find a mutant enzyme that no longer responds to its allosteric activator, where, in the amino acid sequence domains that make up the enzyme, would you expect to find this mutation (change in amino acid?
A.
At either the N or C terminus
B.
in the exact center of the protein
C.
inside the catalytic domain
D.
in allosteric activator domain
E.
somewhere outside of the catalytic domain
Question #24
Fill in blank from following options _____ scans the specimen with a focused laser beam to obtain a series of two-dimensional optical sections, which can be used to reconstruct an image of the specimen in three dimensions. The laser excites a fluorescent dye molecule, and the emitted light from each illuminated point is captured through a pinhole and recorded by a detector. What type of microscopy from the following options best described best option that can filled in
A.
phase-contrast
B.
confocal
C.
scanning electron
D.
transmission electron
E.
bring-field
F.
fluorescence
Question #25
If one strand of a DNA molecule has the sequence of bases B’ATTGCA3’ the other complementary strand would have the sequence ________
A.
5’TGCAAT3’
B.
5’TAACGT3’
C.
5’UAACGU3’
D.
3’UAACGU5’
E.
5’UGCAAU3’
Question #26
You are virologist interested in studying the evolution of viral genomes. You are studying two newly isolated viral strains and have sequenced their genomes. You find that genome of strain 1 contains 25% A, 55%G, 20% C and 10% T. You report that you have isolated a virus with a single – stranded DNA genome. Based on what evidence can you make this conclusion
A.
single-stranded genomes always have a large percentage of purines
B.
Single-stranded genomes have a higher rate of mutation
C.
using the formula : G-A=C+T
D.
Double-stranded genomes have equal amounts of A and T
Question #27
The complete set of information found in a given organism’s DNA is called its ______
A.
genome.
B.
gene
C.
genetic code
D.
coding sequence
Question #28
Figure below clearly depicts a nucleolus, a nuclear structure that looks like a large, dark region when stained. The other dark, speckled regions in this image are the locations of particularly compact chromosomal segments called _____
A.
nucleosomes
B.
chromosome
C.
nuclear pores
D.
heterochromatin
E.
euchromatin
Question #29
The molecular formula for glucose is C6H1206. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration (condensation) reactions?
A.
C18H36018
B.
C3H603
C.
C18H30015
D.
C18H32016
E.
C6H1005
Question #30
The N-terminal of histone H3 can be extensively modified, and depending on the number, location, and combination of these modifications, these changes may promote the formation of heterochromatin. What is the result of heterochromatin formation?
A.
displacement of histone H1
B.
recruitment of remodeling complexes
C.
gene silencing
D.
increase in gene expression
Question #31
Protein folding can be studied using a solution of purified protein and a denaturant (urea), a solvent that interferes with noncovalent interactions. Which of the following is observed after the denaturant is removed from the protein solution?
A.
The polypeptide remains denatured.
B.
The polypeptide returns to its original conformation.
C.
The polypeptide adopts a new, stable conformation.
D.
The polypeptide forms solid aggregates and precipitates out of solution.
Question #32
Which of the following best describes the mechanism by which chromatin-remodeling complexes ‘loosen’ the DNA wrapped around the core histones?
A.
They remove histone H1 from the linker DNA adjacent to the core histone octamer.
B.
They use energy derived from ATP hydrolysis to change the relative position of the DNA and the core histone octamer
C.
They chemically modify the DNA, changing the affinity between the histone octamer and the DNA
D.
They chemically modify core histones to alter the affinity between the histone octamer and the DNA.
Question #33
According to the second law of thermodynamics, all of the following are true except that
A.
entropy increases in a closed system
B.
the synthesis of large molecules from small molecules is exergonic
C.
The Earth is an open system
D.
life exists at the expense of greater energy than it contains
E.
every chemical transformed represents a loss of energy
Question #34
Metabolic control of enzyme catalyzed pathways in cells is most often by
A.
irreversible inhibition and destruction of the enzyme molecule
B.
negative feed-forward inhibition and homosteric activation
C.
negative feedback and allosteric inhibition/activation
D.
competitive and non-competitive inhibition
E.
non-competitive inhibition and positive feedback.
Question #35
Enzymes with a high value for Km exhibit
A.
low affinity for their substrate
B.
. high affinity for their substrate
C.
high Vmax
D.
low velocity of reaction
Question #36
Which of the these statements regarding enzyme is FALSE?
A.
An enzyme maybe used many times over for a specific reaction.
B.
Enzymes are proteins that function as catalysts
C.
Enzymes display specificity for a certain molecules to which they attach or which attach to them
D.
The activity of enzymes cannot be regulated by factors in their immediate
E.
Enzymes reduce activation energy for the reactions they catalyze
Question #37
Within the cell, many chemical reactions that, by themselves, require energy input (have a positive free energy change) can occur because the reactions
A.
are aided by various metal ions that act as catalysts
B.
maybe coupled to the hydrolysis of ATP
C.
take place when the cells are at unusually high temperatures
D.
take place very slowly
E.
are catalyzed by enzyme
Question #38
As determined by the overall change in free energy ΔG = ΔH – ΔS, reactions will be spontaneous when
A.
ΔH and ΔS are both positive and TΔH >H
B.
ΔH - T ΔS <0
C.
ΔH - T ΔS >0
D.
things are moving from higher to lower concentration
E.
ΔH - T ΔS =0
Question #39
Energy required by the cell is generated in the form of ATP. ATP is hydrolyzed to power many of the cellular processes increasing the pool of ADP. As the relative amount of ADP molecules increases, they can find to glycolytic enzymes, which will lead to the production of more ATP. The best way to describe this mechanism of regulation is _____
A.
feedback inhibition
B.
oxidative phosphorylation
C.
substrate-level phosphorylation
D.
allosteric activation
Question #40
The phosphorylation of a protein is typically associated with a change in activity, the assembly of a protein complex, or the triggering of a downstream signaling cascade. The addition of ubiquitin, a small polypeptide, is another type of covalent modification that can affect the protein function. Ubiquitylation often results in _____________
A.
protein secretion
B.
protein degradation
C.
nuclear translocation
D.
membrane association
Question #41
When there is a well-established segment of heterochromatin on an interphase chromosome , there is usually a special barrier that prevents the heterochromatin from expanding along the entire chromosome. Gene A, which is normally expressed underwent Chromatin remodeling in response to a stimulus. None of the daughter cells produced after this recombination event express Gene A, even though its DNA sequence is unchanged. This phenomenon is an example of
A.
Euchromatin depletion
B.
barrier destruction
C.
heterochromatization
D.
epigenetic inheritance
Question #42
Although the chromatin structure of interphase and mitotic chromosomes is very compact, DNA-binding proteins and protein complexes must be able to gain access to the DNA molecule. Chromatin-remodeling complexes provide this access by _____
A.
denaturing the DNA by interfering with hydrogen-bonding between base pairs.
B.
recruiting other enzymes
C.
modifying the N-terminal tails of core histones
D.
using the energy of ATP hydrolysis to move nucleosomes
Question #43
Catalysis by enzymes requires two functions. Vmax measures
A.
the rate of the reaction at ½ the maximum rate
B.
recognition of the substrate by the enzyme
C.
the maximum velocity of the catalytic reaction
D.
the rate of product release by the enzyme
Question #44
Isoelectric focusing is a common method for separation of proteins. In isoelectric focusing proteins are separated in the following gradient ?
A.
A pH gradient
B.
A density gradient
C.
A salt gradient
D.
A temperature gradient
Question #45
What is/are variable structure(s) of a nucleotide?
A.
The sugar
B.
The phosphate group
C.
The base
D.
The sugar and the base
E.
All nucleotide are the same
Question #46
The flow of genetic information is controlled by a series of biochemical reactions that result in the production of proteins, each with its own specific order of amino acids. Choose the correct series of biochemical reactions from the options presented here
A.
replication, translation, transcription
B.
translation, transcription, replication
C.
translation, replication, transcription
D.
replication, transcription, translation
Question #47
The tertiary structure of a protein is the _______
A.
bonding together of several polypeptide chains by weak bonds
B.
organization of a polypeptide chain into an a-helix or β-Pleated sheet
C.
unique three-dimensional shape of the fully folded polypeptide
D.
order in which amino acids are joined in a polypeptide chain
E.
overall protein structure resulting from the aggregation of two or more polypeptide subunits
Question #48
Fred Griffith studied two strains of Streptococcus pneumonia, one that causes a lethal infection when injected into mice, and a second that is harmless. He observed that pathogenic bacteria that have been killed by heating can no longer cause an infection. But when these heat-killed bacteria are mixed with live, harmless bacteria, this mixture is capable of infecting and killing a mouse. What did Griffith conclude from this experiment?
A.
The heat-killed pathogenic bacteria “transformed” the harmless strain into a lethal one.
B.
The infectious strain cannot be killed by heating
C.
The harmless strain somehow revived the heat-killed pathogenic bacteria.
D.
the mice had lost their immunity to infection with S. pneumoniae
Question #49
What is the difference between covalent bonds and ionic bonds?
A.
Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the between charged atoms.
B.
Covalent bonds require carbon whereas ionic bonds do not.
C.
Covalent bonds involve the transfer of electrons between charged atoms; ionic bonds involve the sharing of electrons between atoms.
D.
Covalent bonds involve the sharing of pairs of electrons between atoms; ionic bonds involve the sharing of single electrons between atoms
E.
Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the sharing of protons between charged atoms.
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